Levocetirizine-induced paradoxical fixed drug eruption: A case report with causality assessment

Fixed drug eruptions (FDE) are drug-induced skin reactions that repeatedly occur at the same anatomical site. The skin lesions are usually clear hyperpigmented patches that may develop into blisters. The skin response involves type IV delayed hypersensitivity reactions and is caused by drug-specific memory CD8 T-cells located at the affected skin site. Levocetirizine, an H1-selective second-generation piperazine antihistamine, has a good safety profile and is used to treat the skin reactions. Its nonprescription availability leads to self-medication and unrecognised adverse drug reactions (ADR). FDE due to levocetirizine, as well as with cetirizine, is less common in the literature. This case was reported to our ADR Monitoring Center and causality was assessed as probable and preventable. This case shows that antihistamines such as levocetirizine can trigger FDE in susceptible individuals. Improving clinical awareness through robust Pharmacovigilance activities, educating patients about triggers, and discouraging self-medication are crucial for preventing recurrence.